There is a clear association between exposure to air pollution and cardiac and respiratory health. Variation in the levels of a component of air pollution, particulate matter (a mixture of particles and liquid droplets), correlate with an increase in asthma and COPD exacerbations and cardiac events. We have shown that particulate matter-exposed macrophages induce fibroblast to myofibroblast transformation, a key phenotypic change of airway remodeling which can lead to irreversible airway disease. We hypothesize that particulate matter induces airway remodeling via oxidant-mediated macrophage release of cytokines that trigger myofibroblast differentiation. Exploring the mechanisms of particulate matter-induced airway remodeling is important in providing preventative and therapeutic targets that apply to a broad range of patients. [unreadable] [unreadable] [unreadable]